Invented by WHOI researchers, the ice-tethered profiler climbs up and down a mooring line suspended from the ice, detecting the temperature and salinity at various points in the water column. (Illustration by Jayne Doucette, Woods Hole Oceanographic Institution)

A map of the Arctic ocean includes the proposed locations (yellow triangles) of the two ice-tethered profilers that will be installed by WHOI researchers in April 2007. (Courtesy of Rick Krishfield, Woods Hole Oceanographic Institution)

Researchers Setting Up Observatories to Examine Arctic Changes from Under the Ice

WHOI team headed to the North Pole in April 2007

Researchers from the Woods Hole Oceanographic Institution (WHOI) are
venturing this month to the North Pole to deploy instruments that will
make year-round observations of the water beneath the Arctic ice cap.
Scientists will investigate how the waters in the upper layers of the
Arctic Oceanwhich insulate surface ice from warmer, deeper watersare
changing from season to season and year to year as global climate
fluctuates.

The Arctic expedition is part of a multi-year, multi-institutional
program to establish a real-time, autonomous Arctic Observing Network.
The WHOI researchers will work out of the North Pole Environmental
Observatory, a yearly research camp on the ice that is organized and
led by the University of Washington’s Polar Science Center.

Arctic research specialist Rick Krishfield and engineering assistant
Kris Newhall will lead the WHOI expedition this spring, deploying two
autonomous ice-based observatories between 88° and 90° North. The
observatories are similar in design to moored, open-ocean buoys, though
they will be anchored to the ice instead of the seafloor. The
instruments will slowly drift with the natural movement of the ice
while observing water properties in the top 800 meters of the Arctic
Ocean. The buoys are designed to last three years, about the same
lifespan as the ice floes that support them.

“The goal of the WHOI observing system is to document and understand
annual change through sustained observations of the polar ice pack, the
overlying atmosphere, and upper ocean water properties,” said John
Toole, principal investigator for the project and a senior scientist in
the WHOI Physical Oceanography Department. “Many climate models suggest
the Arctic ice cover will melt within 50 years. We want to measure the
changes in the waterparticularly the layered structure of the oceanin
order to understand what mechanisms might lead the ice cap to melt from
below. The impacts for the ecosystem, the regional and global climate,
and for commerce would be enormous.”

A key element of WHOI’s contribution to the observing system is the
ice-tethered profiler (ITP). Invented by Toole, Krishfield, and
colleagues, the ITP climbs up and down a mooring string each day,
detecting the temperature, salinity, and oxygen content at various
points in the water column. The instrument sends data through the
mooring wire to the surface buoy on the ice, which relays the data by
satellite phone back to researchers in Woods Hole. That data is made
available to the science community and public within hours via the
Internet.

In the past, scientists have studied Arctic waters through expeditions
on icebreakers and ice-locked ships, or by setting traditional moorings
that had to be recovered after months or years of data collection. But
few have tried to send Arctic Ocean data back in real time, year-round,
for multiple years. Six WHOI ice-based observatories have been tested
in the waters north of Alaska over the past three years, and
researchers are confident that they can take the ice-tethered profiler
system all the way to the top of the world.

The water measurements are necessary because there is more than enough
heat stored in the waters entering the Arctic from the Atlantic to quickly melt the entire ice cap. That warmer water, however,
gets sequestered about 300-500 meters down in the ocean, beneath the
“halocline,” a layer that separates the fresher and cooler water near
the surface from the deeper waters. Toole, Krishfield, and colleagues
want to see if that phenomenon is stable or changing with time.

After installing their observatories in April 2007, WHOI researchers
plan to deploy 11 more this summer in collaboration with scientists
from the United States, France, Germany, Japan, Russia, and Canada.
Several more ITPs will be deployed in 2008, as Krishfield, Toole, and
colleagues work toward spreading an array of autonomous observatories
across the region and sustaining them over time.

“We envision putting as many as 20 of these systems in the central
Arctic, distributing them over the pack ice, and having them
simultaneously send data back,” said Krishfield. “That would allow us
to provide a snapshot of the ‘weather’ in the Arctic Ocean for at least
the next couple of years.”

In addition to their own ice-tethered profilers, Krishfield and Newhall
will deploy ice mass balance buoys and an Arctic Ocean flux buoy for
colleagues from the Cold Regions Research and Engineering Laboratory
(U.S. Army Corps of Engineers) and the Naval Postgraduate School. WHOI
is also collaborating with scientists from the University of
Washington, Oregon State University, the Japan Marine Science and
Technology Center, and the National Oceanic and Atmospheric
Administration’s Pacific Marine Environmental Laboratory, all of which
are deploying instruments to measure what is happening above, within,
and below the ice.

The ice camp team will be accompanied by a photographer and writer, who
will file daily dispatches and conduct live teleconferences with
students and museum visitors across the United States as part of an
education effort known as “Live from the Poles.”

Funding for this work has been
provided by the National Science Foundation’s Office of Polar Programs
and Oceanographic Technology and Interdisciplinary Coordination
Program; by the Cecil and Ida Green Technology Development Awards; by
the Woods Hole Oceanographic Institution; and by the James M. and Ruth
P. Clark Initiative for Arctic Research.

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The Woods Hole Oceanographic Institution is a private, independent
organization in Falmouth, Mass., dedicated to marine research,
engineering, and higher education. Established in 1930 on a
recommendation from the National Academy of Sciences, its primary
mission is to understand the oceans and their interaction with the
Earth as a whole, and to communicate a basic understanding of the
ocean's role in the changing global environment.

Originally published: April 16, 2007

WHOI is the world's leading non-profit oceanographic research organization. Our mission is to explore and understand the ocean and to educate scientists, students, decision-makers, and the public.